1. Field of the Invention
The present invention relates to an ignition system for immediately starting a diesel engine when an ignition key switch is placed at an engine start position for actuating a starting motor.
2. Background of the Invention
It is not necessary to install an ignition system into a diesel engine, since the diesel engine compresses injected fuel mixed with intake air and the compressed fuel ignites spontaneously. However, an auxiliary engine starting apparatus needs to be used for facilitating the engine start since it is difficult to start the engine particularly when an engine temperature is low.
A conventional auxiliary engine start apparatus comprises: (a) a low DC voltage supply such as a battery; and (b) an ignition key switch having a first contact connected to a pilot lamp and glow plugs each of which is located within a corresponding combustion chamber, second contact connected to an engine starting motor, third contact connected to an engine stop mechanism for engine stop, and fourth contact for engine continuous running. Each glow plug is located within a swirl chamber of the corresponding engine cylinder in a case of a swirl-chamber type diesel engine. Before starting the engine, the key switch is placed at the first contact position so as to supply the low DC voltage from the low DC voltage supply to the glow plugs. In several ten seconds after each glow plug starts to glow, the key switch is placed at the second contact position to actuate the engine starting motor. At this time, a given amount of fuel is injected into the swirl chamber to mix with a swirling intake air. Therefore, a spray of the injected fuel is brought in contact with the corresponding glow plug to ignite the injected fuel, the ignited fuel being injected into a main combustion chamber via an injection hole.
However, there is a problem in the conventional engine start system described above that it is inconvenient since the engine cranking need to be carried out after several ten seconds have elapsed to glow the glow plugs. In addition, there is another problem that since the glow plugs consume large power, the battery as the low DC voltage supply requires large power so that the conventional auxiliary engine start system has an unfavorable effect on the fuel consumption (the fuel consumption rate depends on the voltage level of the battery).